This invention relates to a machine tool for the machining of workpieces by means of a laser beam which includes a laser beam generator, a laser cutting head and a beam guide for directing the laser beam from the laser beam generator to the laser cutting head. The laser cutting head can be moved relative to the laser beam generator during the processing of the workpiece, and the beam guide includes a beam trombone with a beam bender system which, as the laser cutting head is moved relative to the laser beam generator, is itself movable in synchronization with that positional change.
Machine tools of this type have been described earlier in EP-A-0 559 916 and in JP-A-60199586. In both prior art designs, the laser cutting head is positioned on a bridge spanning the workpiece platform to permit movement in the longitudinal direction of the bridge. The bridge on its part can be moved in the transverse direction. The resulting axes of travel of the laser cutting head define a horizontal plane that covers the working area of the laser cutting head. In both machine tools, a beam trombone serves to keep the path of the laser beam, i.e. the distance of travel for the laser-beam from the laser beam generator to the laser cutting head, at a constant length regardless of the relative movement between the laser cutting head and the laser beam generator. This results in uniform cutting performance of the laser beam across the entire operating range of the laser cutting head. For beam switching i.e. redirection, the prior art beam trombones are each equipped with two beam benders i.e. angled deviation mirrors by means of which the laser beam is guided along what is essentially a U-shaped path within the trombone.
In the machine tool of EP-A-0 559 916, the beam bender system is positioned next to the working area of the laser cutting head in a transverse direction relative to, and movable in the longitudinal direction of, the bridge that guides the laser cutting head. In the longitudinal direction of the bridge the laser beam generator is offset relative to the working area of the laser cutting head.
The machine tool of JP-A-60199586 is equipped with two beam trombones, each with its own beam bender system. One of these beam benders moves jointly with the laser cutting head that is guided by the bridge of the machine in the longitudinal direction of the bridge. The second beam bender can be moved with the bridge in the transverse direction of the latter. Viewed in the direction of travel, the bridge is positioned on one side, the laser beam generator on the other side of the bridge. When the bridge is in an end position of its movement relative to the laser beam generator, the beam bender that is movable with the bridge in the transverse direction of the latter, the bridge itself and the laser beam generator will be positioned one behind the other as viewed in the direction of travel of the beam bender and the bridge.
Because of the configuration described above, both of these prior art machine tools have a relatively large footprint.
On the basis of prior art in this field of technology, it is the objective of this invention to provide a more compact machine design, i.e., with a smaller footprint for an equivalent working area.
It has now been found that the foregoing and related objects may be readily attained in a machine tool for the laser machining of workpieces which include a laser beam generator, a laser cutting head and a beam guide for directing the laser beam from the laser beam generator to the laser cutting head. The laser cutting head is movable relative to the laser beam generator during the machining of the workpiece, and the beam guide includes a beam trombone with a beam bender system. As the laser cutting head is moved relative to the laser beam generator, the beam bender system moves as an adaptive function of such movement of the laser cutting head. In the present invention, the laser beam generator is located in an elevated position relative to the beam bender system of the bottom trombone to permit the beam bender system of the beam trombone to move under the laser beam generator. The beam guide with at least one beam guiding element is positioned in the light path of the laser beam between the laser beam generator and the beam bender system of the beam trombone. It serves to redirect the laser beam emitted by the laser beam generator to the beam bender system of the beam trombone.
The laser beam generator is positioned adjacent the one end of the path of travel of the beam bender system of the trombone, and the beam bender system of the trombone is movable into a position under the laser beam generator. Accordingly, the laser beam generator is positioned in an end zone of the movement of the trombone beam bender and thus near the perimeter of the machine tool and outside the working area of the laser cutting head.
Preferably, the machine tool includes a first guide structure along which the beam bender system of the trombone is movable, and a second guide structure along which the laser cutting head is movable in the direction of a first axis of travel (x-axis). The second guide structure guides the movement of the laser cutting head in the direction of a second axis of travel (y-axis) which extends at an angle relative to the first axis of travel (x-axis). The beam bender system of the trombone is movably guided along the first guide structure on the side of the second guide structure that faces the laser beam generator, and the second guide structure is movable in the direction of the first axis of travel (x-axis) toward the laser beam generator to an end position of its path of travel. When the second guide structure is in the travel end position, the beam bender system of the trombone is moved under the laser beam generator. Thus, when the second guide structure, when in its travel end position, it and the laser beam generator are lined up one behind the other in the common direction of travel of the second guide structure and the beam bender of the beam trombone. Consequently, viewed in that direction of travel, the laser beam generator, the beam bender of the trombone and the second guide structure only take up relatively little space.
Desirably, on the side of the second guide structure facing the beam bender system of the trombone and opposite the second guide structure that occupies its travel end position across from the laser beam generator, the first guide structure has a projection whose length in the direction of the first axis of travel (x-axis) essentially corresponds to the respective dimension of the beam bender system of the trombone and the maximum possible path length over which the beam bender system of the trombone can be moved when the laser cutting head is in motion in the direction of the second axis of travel (y-axis). This permits an appropriately compact system configuration by minimizing the length of the first guide structure.
In a preferred form, the laser cutting head can be moved along a second guide structure which itself is movable jointly with the beam bender of the trombone along a first guide structure. In a preferred design version of the invention, the beam bender of the trombone and the second guide structure are provided with drive units that jointly employ at least one common drive shaft.
The over-under arrangement of the laser beam generator and the beam bender of the trombone makes it possible for the beam bender to move under the laser beam generator to allow a relatively small footprint for the overall system. Moreover, a compact system architecture is also achieved by having the same drive shaft serve to drive both the beam bender of the beam trombone and the laser cutting head.